Electrospun Azido-PCL Nanofibers for Enhanced Surface Functionalization by Click Chemistry

This paper reports highly surface functionalized and “clickable” α,ω-azido-poly­(ε-caprolactone) fibers (f-PCL-N<sub>3</sub>), obtained by classical electrospinning setup. Azide-functionalized PCL was obtained from a commercially available α,ω-poly­(ε-caprolactone)-diol, PCL<sub>2</sub>, and electrospun with a nonderivative high-molecular-weight PCL. Successful chemical modifications of PCL<sub>2</sub> were confirmed by NMR, FTIR and MALDI-TOF mass spectroscopy. The high content of surface azides, as a response to the high electric field applied, was characterized using a colorimetric assay. In addition, azide reduction to amines revealed a nondestructive route for highly amine-functionalized fibers. Fluorescence labeling of f-PCL-N<sub>3</sub> fibers with FITC-alkyne fluorophore proved that the azide groups are mainly surface-localized as well as highly available for click-chemistry coupling.